The Sewer Authority Mid-Coastside (SAM) transports and treats wastewater from several coastal communities in San Mateo County, California. In the spring of 2017, one of SAM’s force mains, the Granada Force Main, experienced a series of ruptures that disrupted operations and negat ively impacted local beaches. Due to its p revious history of breaks, its age, and materials of construction, SAM initiated a program to replace most of the force main to improve system reliability, protect residents, and safeguard the coastal environment.

This challenging project was executed on a short schedule and a limited budget. SAM expedited the design process in parallel with surveying, condition assessment, biological assessment, wetlands delineation, and permitting. The design incorporated durable corrosion resistant materials such as high-density polyethylene (HDPE) pipe and appurtenances and unique construction techniques such horizontal directional drilling to accelerate the construction process.